Leaching apparatus



Patented Dec. 6, 1927.

UNITED STATE-s PATENT OFFICE.

nENnY Y. EAGLE, oF BROOKLYN, NEW Yonx, AssIGNoB oF ONE-HALL' 'ro AEcHEnE WHEELER, oENEw YoEx, N. Y. v v

LEACHING APPARATUS.

Application led June 27, 1923. Serial No. 647,985.

This invention .relates to apparatus such as are used in installationswhere pulverized ore is subjected to the action of leaching sov lutionswith agitation.

In the leaching of various materials, the dissolving of the solubleconstituent of the material is effected in tanks provided withagitators, in which the material and the solution are continuouslyagitated for the length l0 of time necessary to effect the desireddegree of dissolution. Heretofore, the size of particle which such aleaching device could successfully handle has been limited to very1smalll sizes. Moreover,'on4 the largest sizes which have beensuccessfully agitated, the work is only accomplished by maintaining-definite conditions of pulp density-that is, the larger the size ofparticles to be kept in suspension, the thicker must be the pulp.

This limiting factor makes it necessary to grind the ore so as to formvery fine particles, which is an expensive operation. With the largersize particle, requiring pulp of greater density to keep it insuspension, a correspondingly small quantity of solution f per unit ofsolid results.

This latter effect naturally results in a solution carrying largequantities of the soluble material, and which makes the capitalexpenditure of any washing scheme in the resulting separation of thesolids from the liquid, very expensive.

The solid material is agitated with the solvent, continuously flowinginto the agitating tank at one point and out at another point atsubstantially the same rate. The difficulty is Vto get the largerparticles to go to the outlet. Unless they do this, they graduallyaccumulate in the bottom of the tank and in time stop its operation.This necessity of carrying the larger particles to the outlet at thesame rate at which they enter the tank has made it necessary to maintainthe solution in the tank of a comparatively high density so that thesolid particles will not fall rapidly through it, but will be held uplong enough to pass to the outlet, near' the level in the tank. And evenwith a comparatively dense solution the size of the solid particleswhich the ordinary machine can andle is limited. A portion of thesolution, in thc subsequent Washing operations, is always held in theapparatus, and becomes practically part of the capital thereof, and thisretained portion of the solution is the more valuableas the solutionisdenser.

By my invention; I am enabled to use a less dense solution than waspossible before my ap aratus, and I am enabled to carry through theapparatus continuously solid particles of larger size than formerly,thus saving considerable expense in the grinding of solid material.

An embodiment of the invention is illustrated in the accompanyingdrawings in which- Fig. 1 is a vertical longitudinal'section;

Fig. 2 is a top plan thereof and Fig. 3 is a 1an of a detail.

e apparatus comprises a substantially cylindrical wall 10 having abottom l2 through the center of which extends a pipe 14 connected withsuitable air supply line 16 having'a control valve 18 located therein.Centrally disposed within the tank 10 is a tubular shaft 20 havingoutwardly extending trough-like arms 22 and 2.4 connected at its upperend. The shaft 2() and arms 22 lrotate together and are ldriven by apulley 26 secured to a stub shaft 28 fast lin a hub 30 which is suitablysecured to the arms 22 and 24. The pulley 26 is driven by a belt 32connected to a motor or other suitable source of power, notl shown.Bearings 34 and 36 of any usual or suitable design are provided forrotatably mounting the shaft 20 and the parts carried thereby.

At its lower end, the shaft has, secured thereto outwardly extendingarms 38 provided with prongs or projections 40 which serve to rake theparticles of material which 'fall to the bottom of the tank.-

The projections 40 are inclined as shown in Fig. 2 so that theyVgradually force the large particles of solid material on the bottom tothe center and to the inlet of the airlift.

Near the upper end of the tank, but below .the trough-like arms 22 and24, I mount an annular launder 42 which is adapted to receive the pulpwhich is discharged from the arms 22 and 24 as the latter rotate, itbeing apparent that the pulp discharged from the rotating troughs 22 and24 will be distributed quite uniformly throughout the length of theannular launder.

The launder 42, as shown in Fig. 2, does not extend fully around theinner periphery of the tank but is formed with end walls 44 and 46leaving an opening 48 into which extends the inlet launder so that thematerial flowing therefrom enters directly into the tank'and not intothe peripheral launder 42. The launder 42 is adapted to discharge partof. its contents into an outlet launder 52 and part of its contents intothe tank through an -outlet port 54 formed in the vertical wall 43 ofsaid launder 42.

` This .general type of apparatus, in which 2 the material is clrculatedby forcing it conthe level, as in previous machines.

tinuously from theY bottom to the top is known 'and there are variousmachines operating on this principle. But the material (or most of thematerial) lifted to the top has .generally ,been discharged directlyinto `the tank again; And in order that it shall all pass out of thedischarge launder it has been necessary to make the solution so denseand the particles so finethat they would pass from the upper part of thesolution into the discharge launder. It is clear that any solid particlewhich enters the tank and which at the density of the pulp in the tankis incapable of being lkept in suspension, will eventually find its wayto the bottom of the tank. In agitating leaching apparat-us heretoforeconstructed-,such particles have accumulated onthe tank bottom and havefrequently resulted in breaking the agitating mechanism or otherwiserendering it inoperative. Even in cases where the particles have beencarried upward by the a'irlift` their quick settling properties haveprevented them froml being distrlliirged.l

In my,l improved. apparatus the material Vflows in at the launder 50,the particles which settle on the bottom are carried to the centerandthe airlift carries them to a point above But, instead of dischargingthe lifted particles and solution, or most of them, back 1nto the tankdirectly, I discharge substantially or approximately all of the pulp,that is the particles and the lsolution into the annular launder orreceiver 42. Thence the pulp is discharged, AVwithout opportunity. forthe heavier particlesto separate from thelighter,

into the discharge launder 52 at substantially the same ratev at which'the solution and the solids enter Ythe tank; the excess received bythekannular launder being` returned to the an Y The discharge from theannular launder into the tank isover a low weir 56 calculated to deliveiinto the tank the excess of solution carried Ytof-the annular launderover that the outlet launder 52. The risel in the level willoccur ofcourse only during the period in which the discharge continues tobe less1 than the feed. We assumethe-feed to be constant. While the level -inthe tank is below the Aweir a Vcertain percentage of the solution willflow out through the launder 52, the quantity which will be dischargedin this way being dependent on the height of the weir. Ifthe Weir-is toohigh the outflow will be greater than the 'iniow through the launder 50.If the weir is lowered progressively, the'outfiow through the launder 52will be reduced to a point where it is less than the inflow, and thelevel in the tank will gradually'rise to the Weir and slightly above it.thus increasing the outflow to the launder 52 until a balance is reachedand thelevel in the tank remains stationary slightly above the weir.

The port 54 may be adjustable, as shown in Fig. 3. For thispurpose, Iwould pro-l vide flanges 58 at the sides for the introduction of platesof different sizes. to reduce the opening accordingly. Generally theopenmakes it unnecessary to secure the accurater sizing of the materialswhich was formerly required. The apparatus may be used also for pulp ofvdifferent densities, which in ordinaryv leaching work permits .the useoflow grade solutions and of a cheap washing installation. y

. As I have said' above, there are various Astyles of agitator in whichthe ulp is agitatedand then forced from a ower to an upper zone andcirculated thus through the tank.' My invention-is applicable to variousagitators working-on this principle, and improves their operation andtheir capacities as described by receiving the pulp thus lifted to anupper zone .and discharging it at the desired rate without giving thesolid particles therein an opportunity to settle into the genk againbefore reaching the outlet launer. Y .The A4annular launder maybesubstituted by receptacle's'of various other shapes according tothedesign of the agitator to whichv it isA to'be applied. And the vtermlaunder herein, is used generally to-indicate a `variety ofv'receptacles and pipes which will serve the Ysame purpose. Also theapparatus may comprise other known means 'of agitation and of directingthe larger particles at the bottom to the air lift.

In the case illustrated the annular launder is arranged to receiveapproximately or substantially all the pulp lifted. But it will beappreciated that it may be arranged'to receive less than .this and stillfunction satisfactorily. It is important that it shall be of such Sizeas to hold a substantial proportion of the coarser materialwhich is inprocess of passing'through the tank at any given time. Of the -materiallifted into the annular launder, the coarser particles move the moreslowly toward the outlet. Thus after a short initial period the annularlaunder will carry at all times a sufficient proportion of the coarserparticles to substantially diminish the tendency to choke the air lift.

Though I. have described with great particularity the details o'f theembodiment of the invention herein shown, it is not to be construed thatI am limited thereto, as

- changes in arrangement and substitution of equivalents may be made bythose skilled in the art without departing from the invention as.definedA in the appended claims.

What I claim is:

1. A leaching apparatus comprising a tank provided with means foradmitting and discharging pulp, means for agitating and forcing pulpfrom a lower zone of the tank to an upper zone and means adapted toreceive and hold more lifted nlp than is introduced through saidadmitting means in a given time and adapted to discharge part of itdirectly and return part of it to the 2. .A leaching apparatuscomprising a tank with 'inlet and outlet launders near the top thereof,means for lifting-the pulp from a lower to an upper zone in the tank anda receiving launder `for the pulp thus lifted having a discharge openinginto said outlet launder, and having also a discharge opening into thetank. l

4. A. leaching apparatus comprising a tank having at a point above thenormal level of the pulp a receiver arranged to discharge part of itscontents from the tank and to return part to the tank, and means forlifting agitated pulp into said receiver.

5. A leaching apparatus having an air` lift adapted to distribute thepulp in a circular zone near the top of the apparatus and a receiver forthe pulp so distributed, saidre ceiver having a discharge opening to apoint outside of the apparatus and having an opening discharging backinto the. apparatus and adapted to maintain the level thereof.

6. A leaching apparatus having an air lift with a rotary member adaptedto distribute the pulp in a circular zone near theI top of the tank andan annular receptacle Ahaving a discharge opening to a point outside ofvthe tank, said receptacle being adapted to receive and to holdasubstantial proportion of the coarser material which is inthe tank atany given time.

In witness whereof, I have hereunto signed my name.

' HENRYY. EAGLE.

